As a wireless communication system has been advanced and a demand for portably available high-capacity multimedia contents has been increased, many efforts have been made to increase a data transfer rate of a wireless communication system. Representative examples are a Wibro which can use the Internet during a high-speed movement, and a wireless LAN which can watch high-quality images during a low-speed movement in real time. A wireless LAN will be exemplarily described. The IEEE 802.11a/g standard supports a 54 Mbps physical layer data rate through a single antenna at a 20-MHz bandwidth in a 2.4-GHz or 5-GHz band. The IEEE 802.11n standard supports up to four antennas and a 40-MHz bandwidth and thus supports a 600-Mbps physical layer data rate.
As the next generation wireless LAN for ensuring a higher data rate, a next version of the IEEE 802.11n standard is under discussion. In general, the IEEE 802.11n standard is called a high throughput (HT) mode, and the IEEE 802.11a/b/g mode is called a legacy mode. On the other hand, the standard which has been newly discussed in the IEEE 802.11ac/ad is called a very high throughput (VHT) mode.
To process high-rate data with high reliability, a recent wireless communication system has become more complicated, as compared to a conventional art. As a data rate improvement technique, a channel bonding technique which bonds multi-channels and transmits data over the bonded channels is applied. In addition, a higher order modulation scheme and channel coding scheme have been introduced. In addition to a technique which increases a data rate with the use of multi-antennas, a technique which simultaneously transmits data to multi-users has been researched and developed. Due to such a complicated transmission/reception technique, the size of a wireless communication system increases and the circuitry thereof becomes complicated. Furthermore, since data is transmitted using a wider bandwidth than a conventional art in order for a high-rate data transmission, the required operating frequencies of a digital-to-analog converter (DAC), an analog-to-digital converter (DAC), and a modem processor have been increased. On such a technical background, a power save design for a dynamic channel bandwidth utilization technique and a high-data-rate wireless communication system has become an important issue as a receiver optimization technique for efficiently using finite frequency resources and reducing noise.
In addition, a wireless LAN operates at a limited frequency band. A 160-MHz bandwidth (bonding of eight 20-MHz bands) is relatively very wide band. Accordingly, interference and coexistence problems may occur between stations which support various standards. Therefore, there is a need for a technique which optimizes a receiving end by informing stations of preceding information through a control frame prior to a data frame in order to detect a multi transfer mode frame with high reliability.